Metal object separation system



United States Patent [013,543,930

[72] Inventors Wilfred Richard Delbridge; I

Oiva A. Wienola; Robert K. Young, York, Raerences Cited Pennsylvania UNITED STATES PATENTS I 1 PP 753,621 2,317,351 4/1943 Andalikiewicz et al 194/100 PM z- 1968 3,147,839 9/1964 White, Jr 194/100 [45] Patented Dec. 1, 1970 [73] Assignee American Machine & Foundry Company Examm"stanl'ey Tollbefg a corporation New Jersey Attorneys-George W. Pnce and Barry R. F1shk1n [54] METAL OBJECT SEPARATION SYSTEM 4 Claims, 4 Drawing Figs.

[51] Int. B07c 5/34 [50] Field ofSearch 133/3;

194/100, 100.5, 101; 209/11 1.9, (inquired) ABSTRACT: The invention comprises means for projecting a metal object against an anvil, means for detecting the dominant frequency of vibration caused thereby, an electromagnetic coil, and means for activating the electromagnetic coil in response to the detection of a predetermined frequency.

Patented Der "1,1910

Shoot a or 3 loo such as planchets, blanks, etc. a

1 1 METAL OBJECT SEP R TION SYSTEM BACKGROUND SUMMARY It is, therefore, an object of this invention to provide a highspeed metal object separation system.

It is a further'object to provide a metallic object separation system including an electronic separating means.

It is a more particular object of this invention to provide an electromagnetic separating device operable to separate metallic objects without physically engaging them.

It is a still more particular object of this invention to provide over an electronically controlled electromagnetic coil, wherein coins of one characteristic are propelled into a different trajectory than those of other characteristics.

In accordance with these and other objects, the' invention comprises means for projecting a metal object against an anvil, means for detecting the dominant frequency of vibration causedther'eby, an electromagnetic coil, and means for activating the electromagnetic coil in response to the detection of a predetermined frequency.

DESCRIPTION OF DRAWINGS FIG. 1 is a plan view of a preferred embodiment of the invention.

FIG. 2 is a sectional elevation view of an electromagnetic coil according to the invention taken along line 2 -2 of FIG. 3'. FIG. Sis a plan view with portions broken away of the electrornechanical coil of FIG. 2.

' FIG. 4. is a schematic block diagram .of a preferred circuit for the invention.

nascnr'r'rron orrns PREFERRED EMBODIMENT With reference to the drawings, a preferred embodiment of the invention is'hereinsfter'deseribed as a' separator for coins of like denomination'but different metallic makeup, but it is to be understood that the invention is not limited to the separation of coins and can be utilized to separate any metal objects,

- Referring now to FIG. 1, apparatus according to the invention may comprise an Abbott coin feeder for feeding coins one at the time to the entrance end of a track 12. A feed wheel 14 is mounted above the leading end of track 12 such that the periphery thereof engages coins in the track and advances them therealong to a rate wheel 16. The rate wheel is also mounted above the track andv extends therein to engage coins in the track to advance them further therealong. The rate wheel controls theme with which coins are inspected and separated. Coins fed along the tracks from rate wheel 16 are engaged by impeller wheels '18 and 20 which hurl the coins' down the remaining portion of the track and out the exit end thereof at a speed of upwards of 250 inches per second.

An anvil 24 is mounted adjacent the trailing end of the track in a position such that coins hurled from the track by the impeller wheels strike the anvil, are deflected to a new path and are caused to vibrate. A transducer 26 is mounted adjacent to anvil 24 and just above'the path of coins deflected by the anvil. The transducer is operable to convert the vibrations of the coins into an electric signal of .the same frequency."

I a high-speed system for separating coin's by projecting them An electromagnetic coil 28 is mounted just under the deflected path of the coins beyond transducer 26, and upon the activation thereof is operable to form a high intensity magnetic field which functions to induce current in the coin which creates a magnetic field surrounding the coin passing thereover that is counter to the one emanating from the coil. thus propelling the coin upwardly out of its normal path. A circuit 30 (FIG. 4) is provided between transducer 26 and coil 28 to activate thecoil only upon the detection by the transducer of a predetermined frequency. Apair of collection chutes 32 and 34 are mounted in alinement with anvil 24. The collection chutes are positioned such coins that do not vibrate at the predetermined frequency and thus do not have their trajectory changed by coil 28 fall into chute 32 while coins that have been acted upon by the coil will fall into chute 34.

More specifically, theAbbott coin feeder 10 includes a rotatable (counterclockwise as seen in FIG. 1) base plate 38 and a substantially circular sidewall 40. An aperture 42 is provided in the sidewall 38 adjacent the leading end of track 12. A plate 44 is mounted past the aperture to direct coins into the track.

Feed wheel 14 is mounted on a shalt. A drive shaft 48 is provided in axial alinementwith shaft 46 and-the latter is driven by the former through a clutch 50.

Both the Abbott coin feeder and drive shaft 48 are driven by a motor 52. The motor includes an output shaft 54 which is parallel spaced relationship with drive shaft 48 and a drive shaft 55 for the Abbott coin feeder. Spaced drive belt mounts 56 and 58 are mounted on output shaft 54 and drive shaft 55, respectively, and a drive belt 60 transmits the rotary motion of the former to the latter. A second drive belt mount 62 is mounted on shaft 55 in spaced relationship with a drive belt mount 64 on drive shaft 48. A drive belt 66 transmits the rotary motion of the shaft 55 to drive shaft 48. Of course, the drive belt mounts and drive belts just described could just as well within the scope of the invention be sprockets and chains or any other means for transmitting power to shafts 55 and 48.

Upon activation of motor 52, the Abbott coin feeder feeds a succession of coins to track 12 whereat feed wheel 14, which extends into the track from the top thereof through an aperture 68,;advances the coins in a row to rate wheel 16. Since the feed wheel rotates faster than the rate wheel, the coins will backup behind the rate wheel. In this situation, clutch 50 will prevent jam-ups in the apparatus by halting the rotation of shaft 46 until a coin has been advanced past the rate wheel,

. whereupon the row. of coins willbe advanced. i

' The rate wheel controls, by'the a" gular velocity of its rotation, the'rate at-which-coins are 'inspecteda'nd separated by circuit30 and electromagnetic co'il28 respectively. The rate wheel, which also extends through aperture68 to engage the coins in the track, is mounted on shaft 70 which is the output shaft of a controllable variable speed device 7 2.

Impeller wheels 18 and 20 extend into the track from the sides thereof and engage coins fed past the rate wheel to hurl them down the track at high speeds. The high-angular velocity of the impeller wheels are imparted thereto by shafts 73 and 82, respectively. Thus, the position of the'impeller wheels with respect to the ferent sizes. I

The anvil'24 is mounted adjacent the exit end of track 12.

track may be adjusted for engaging coins of dif- The operative face 86 of anvil 24 is vertically disposed at an I acute angle to the pathof coins leaving the track. Thus, the

edges'of coins projected down the track by the impeller wheels strike the anvil. This changes their path in the horizontal plane andcauses the coins to vibrate, or-ring."

Transducer 26, which is preferably, but not limited to, a

' microphone, is mounted above the deflected path of the coins by a stand 88. Stand 88 is mounted on a base 90 which also supports the anvil 24. The electromagnetic coil 28 is mounted in base 90, with its upper surface being flush therewith;

for the same purpose.

Referring now to FIGS. 2 and 3, electromagnetic coil 28 is mounted in a housing 100, which in turn is mounted in base 90. Housing 100 includes a recess 102 in the upper surface thereof to receive the coil. The coil itself comprises alternate windings of strips of copper and Kapton, the latter being a dielectric manufactured by the DuPont Company. The coil is mounted in recess 102 such that the inner end thereof is connected to a centrally located terminal 104. The peripheral end of the coil is extended out near the periphery of the housing and connected to a terminal 106.

The coil is imbedded in an epoxy bed 108 to aid in dissipating heat. Cooling is provided by passing water through an annular chamber 110 in the housing. A separating wall 112 is mounted in the annular chamber to define a path for the water coolant. The water is injected into chamber 110 through a feed line 114 and exits through a conduit 116. A cap 118 is provided for the housing and forms one end of the chamber 110. Cap 118 includes ports 120 and 122 to transmit water to and from the chamber from the infeed and exit lines 114 and 116 respectively. FIG. 4 shows a schematic block diagram of circuit 30. The circuit operates to activate electromagnetic coil 28 in response to the detection of a predetermined frequency of vibration adjacent anvil 24 by transducer 26. The circuit 30 described immediately hereinbelow is operative to separate two types of coins that therefore will oscillate at two different dominant or resonant frequencies.

The output signal of transducer 26, which is a microphone, is sent to a buffer amplifier 130 which has an output which serves as the input for two band pass filters, 132 and 134. The center frequencies of the band pass filters depends upon the objects being separated, but the Q of the two filters should be such that there is at least 50 db. separation at the center frequency. The output signals of the filters are each fed to separate amplifier/integrator circuits; 136 and 138 respectively.

Each amplifier/integrator circuit consists of a variable gain section. The integrator section requires an external gating not the coil will be activated. For explanation purposes, assume amplifier/integrator 136 is connected to the inverting input and amplifier/integrator 138 is connected to the noninverting input. Then, if the signal level of amplifier/integrator 138 is greater than amplifier/integrator 136 the comparator output at the strobe time goes to a positive level for the duration of the strobe pulse. If the converse is true, i.e., the signal level of amplifier/integrator 136 is greater than that ofamplifier/integrator 138, the comparator output remains negative when the strobe is received. Thus the comparator output is a bilevel function of the integrator outputs and thus the sr strength of the coin vibrations at the two band pass filter center frequencies.

Therefore, where selecting band pass filters, the center frequency of the band pass filter connected to the amplifier/integrator connected to the noninverting input of the comparator is such to coincide with the dominant or resonant frequency of the coin having the particular metallic makeup sought to be actedupon by the coil 28. The center frequency of the other band pass filter is selected such that it coincides with the dominant or resonant frequency of a coin having another metallic makeup.

Since the strobed comparator output occurs at a time when the coin has traveled just a shortdistance and is not yet in a suitable position for physical sorting by coil 28, the determination which has been made must be stored until the coin is in a proper location in its trajectory. The storage or memory capa- I when the output of reset pulse generator 150 drops to zero it pulse to integrate. During that pulse, a relay contact is opened (which normally shuts the capacitive feed back element of an operational amplifier) to produce a signal proportional to the integral of the input signal to that section.

The external gating pulse is supplied to the integrator sections of the amplifier/integrators 136 and 138 when the leading edge of the coin interrupts the light beam on photocell 92 and activates the photo diode thereof. The pulse is sustained by a gate interval timer 142 for a period of approximately 3% milliseconds During this time each amplifier/integrator output is integrating the electrical signal which is proportional to the mechanical energy at the frequency consistent with the center frequencies of the band pass filters in the coin passed through the respective band pass filters. The output of the two amplifier/integrators 136 and 138 serves as the input to a comparator 148, with amplifier/integrator 136 being connected thereto through contact 146b of a switch 146.

The comparator is the element that determines whether coil 28 will be actuated. The center frequencies of the two band pass filters are selected such that one will pass the signal generated by coins having a desired metallic makeup and the other will pass the signal generated by coins of an undesired metallic makeup. The respective amplifier/integrator integrate these respective signals.

The output of the comparator is clamped to a negative level until a strobe signal is received from the gate interval timer 142. This strobe signal occurs at the end of the gating pulse. The output polarity of the comparator after the strobe signal is received is a function of relative levels of the integrator outputs at that time. This output polarity determines whether or remains zero until it is reset by a signal derived from the interruption by the coin of second photocell 94.

Photocell 94, is in a position such that the coin is centered over the coil 28 when the beam is broken. The signal from the photocell is processed thru a pulse shaper 156 in order to produce a fast rise pulse of the proper magnitude. This pulse is transmitted to a SCR driver 152.

The SCR driver 152 produces an output when a pulse is received from pulse shaper 156 and the level from the reset pulse generator is zero. When a pulse is produced by SCR driver 152, another pulse-is also produced which returns the level of the reset pulse generator 150 to the +20 volt positive level.

The output pulse of SCR driver 152 is transmitted to the gate of a high voltage silicon controller rectifier 160 through an isolating SCR drive transformer 158. When SCR 160 is gated ()N", the stored charge in a capacitor bank 162 is discharged through the electromagnetic coil 28. The coil induces currents in the coin as it passes over the coil when the capacitor bank is discharged. These currents in the coin are in such a direction as to set up a magnetic field counter to the one emanating from the coil, thereby producing a repulsion force between the coil and the coin. When this occurs, the normal trajectory of the coin is altered such that it now assumes a higher trajectory. The difference in trajectories can be adjusted to get the desired physical separation by adjusting the voltage to which the capacitor bank is charged.

The switch of SCR 160 reopens when the anode voltage thereof drops below the cathode voltage, approximately 200- microseconds after the SCR started to conduct. This is due to overshoot of the capacitive/inductive circuit.

When the switch of the SCR is so opened, capacitor bank 162 can be recharged from a variable three phase high voltage power supply through a limiting resistance 166. The power supply includes a three phase input 168, a variable auto transformer 170, a delta-Wye power transformer 172 and a full wave rectifier 176.

Circuit 30 can also operate to separate good coins from defective ones. It has been determined that coins that are defective in poor bonding of heterogenous layers, blisters on the outside layer, missing heterogenous components (i.e., entire layers missing), partial delamination, etc., cause a change in the fundamental mode of the natural frequency of vibration. Generally this change is such that the frequency is significantly lower.

The technique for detecting delaminated coins, blanks, or planchets is essentially the same as that for separating two types of good coins as previously explained. The singular difference is that instead of the output of two filter/amplifier/integrator channels being compared, only one filter/amplifier/integrator output is compared against a fixed level. Thus switch 146 is connected to its contact 146a. In order that the machine operate in fail safe manner (i,e., machine failure causes inspected pieces to be rejected) the output of amplifier/integrator 138 is fed to the noninverting input of comparator 148.

To summarize, the output of buffer amplifier 130 passes thru band pass filter 134. The center frequency of the filter 134 is that at which a good" coin oscillates when it is in its fundamental mode of vibration. The filter output feeds the comparator noninverting input.

A DC fixed bias 144 is fed into the inverting input of the comparator. The voltage level of this bias is experimentally determined by ringing" good planchets or coins, observing the output of amplifier/integrator 138 at the time of the strobe pulse and setting the bias level slightly below that level.

The rest of the machine logic is identical to that as used for separation in theory and hardware.

We claim:

1. A method of separating metal objects, which comprise the steps of:

causing a metal object to vibrate;

determining whether said metal object is vibrating in a predetermined frequency range; and

projecting a magnetic field in response to the determination that the metal object is vibrating in said predetermined frequency range, said magnetic field inducing a counter magnetic field in the metal object and thus causing the repulsion of the metal object toward a collection area.

2. A method according to claim 1 wherein the step of determining whether said metal object is vibrating in a predetermined frequency range comprise the steps of:

transducing the ringing of the metal object into an electric signal;

filtering the signal;

amplifying and integrating the signal;

selecting a fixed signal level source that produces a signal level just below that produced by a filtered, amplified and integrated signal from a metal object vibrating in the predetermined frequency range; and

comparing the level of the filtered, amplified and integrated signal from the vibrating metal object to the fixed signal level.

3. Apparatus for separating metal objects, which comprises:

means for causing a 'metal object to ring at its natural frequency;

transducer means for changing the ringing of the metal object to an electrical signal;

filter means for filtering out all signals except those of a predetermined frequency;

means for comparing the level of said filtered electrical signal with a fixed signal level;

an electromagnetic coil; and

means for activating the electromagnetic coil upon detection by the comparing means of a predetermined filtered signal level.

4. Apparatus according to claim 3, wherein: said coil is activated by a silicon controlled rectifier; and the silicon controlled rectifier is triggered by the detection of a metal object over the center of the coil. 

